Phase-noise reduction technique using frequency-to-current conversion with baseband integration

Abstract

A circuit for measurement of a phase noise of an oscillator may include the oscillator to generate a first signal having the same oscillation frequency as an instantaneous oscillation frequency of the oscillator. The circuit may include a first circuit that is configured to generate a second signal from the first signal. An instantaneous amplitude of the second signal may be related to the oscillation frequency of the first signal. A second circuit may be configured to integrate the second signal to generate a third signal. The third signal can be a measure of the phase noise of the oscillator. The third signal can be used to cancel some or all of the phase noise of the oscillator.

What is claimed is: 
     
       1. A circuit for measurement of a phase noise of an oscillator, the circuit comprising:
 a first circuit configured to generate a second signal from a first signal, wherein the first signal is generated by the oscillator at a frequency (ω c ) and includes a phase noise (φ n (t)) of the oscillator, and wherein an instantaneous amplitude of the second signal is proportional to a summation of the frequency (ω c ) of the first signal and a time derivative of the phase noise of the first signal (dφ n (t)/dt); and 
 a second circuit configured to integrate the second signal to generate a third signal, the third signal being a measure of the phase noise of the oscillator. 
 
     
     
       2. The circuit of  claim 1 , wherein the first circuit is configured to utilize the first signal to generate at least one of a current signal or a voltage signal based on the oscillation frequency of the first signal. 
     
     
       3. The circuit of  claim 1 , wherein the first circuit is a frequency-to-current converter circuit that is configured to utilize the first signal to generate a current signal based on the frequency of the first signal. 
     
     
       4. The circuit of  claim 1 , wherein the first circuit is a frequency-to-voltage converter circuit that is configured to utilize the first signal to generate a voltage signal based on the frequency of the first signal. 
     
     
       5. The circuit of  claim 1 , wherein the second circuit is configured to integrate the second signal and to eliminate an effect of the noiseless oscillation frequency on the third signal. 
     
     
       6. The circuit of  claim 1 , wherein the second circuit comprises an integrator circuit configured to integrate the second signal and to substantially attenuate near-zero frequency signals. 
     
     
       7. The circuit of  claim 1 , wherein the first circuit comprises a switched-capacitor circuit configured to utilize the first signal to generate at least one of a current signal or a voltage signal based on the oscillation frequency of the first signal. 
     
     
       8. The circuit of  claim 7 , wherein the switches of the switched-capacitor circuit are controlled by the first signal and an inverted version of the first signal. 
     
     
       9. The circuit of  claim 1 , wherein the first signal comprises a time varying voltage signal derived from an output signal of the oscillator. 
     
     
       10. A method for measurement of a phase noise of an oscillator, the method comprising:
 deriving a first signal from the oscillator, wherein the first signal is generated by the oscillator at a frequency (ω c ) and includes a phase noise φ n (t)) of the oscillator; an instantaneous of the oscillator; 
 generating a second signal from the first signal, wherein an instantaneous amplitude of the second signal is proportional to a summation of the frequency (ω c ) of the first signal and a time derivative of the phase noise of the first signal (dφ n (t)/dt); and 
 integrating the second signal to generate a third signal, the third signal being a measure of the phase noise of the oscillator. 
 
     
     
       11. The method of  claim 10 , wherein the generating of the second signal from the first signal comprises generating at least one of a current signal or a voltage signal based on the oscillation frequency of the first signal. 
     
     
       12. The method of  claim 10 , wherein the generating of the second signal from the first signal comprises using a frequency-to-current converter circuit and utilizing the first signal to a generate a current signal based on the frequency of the first signal. 
     
     
       13. The method of  claim 10 , wherein the generating of the second signal from the first signal comprises using a frequency-to-voltage converter circuit and utilizing the first signal to generate a voltage signal based on the frequency of the first signal. 
     
     
       14. The method of  claim 10 , wherein the integrating of the second signal comprises eliminating an effect of the noiseless oscillation frequency on the third signal. 
     
     
       15. The method of  claim 10 , wherein the integrating of the second signal comprises using an integrator that substantially attenuates near-zero frequency signals. 
     
     
       16. The method of  claim 10 , wherein generating the second signal from the first signal comprises using a switched-capacitor circuit and utilizing the first signal to generate at least one of a current signal or a voltage signal based on the frequency of the first signal. 
     
     
       17. The method of  claim 10 , wherein the deriving of the first signal from the oscillator comprises deriving a time varying voltage signal from an output signal of the oscillator. 
     
     
       18. The method of  claim 10 , wherein generating the second signal comprises using a switched-capacitor circuit and configuring the switched-capacitor circuit to utilize the first signal to generate at least one of a current signal or a voltage signal or a current signal based on the oscillation frequency of the first signal. 
     
     
       19. A non-transitory machine-readable medium embodying instructions that, when executed by a machine, allow the machine to perform a method for measurement of a phase noise of an oscillator, the method comprising:
 deriving a first signal from the oscillator, wherein the first signal is generated by the oscillator at a frequency ((ω c ) and includes a phase noise (φ n (t)) of the oscillator; 
 generating a second signal from the first signal, wherein an instantaneous amplitude of the second signal is proportional to a summation of the frequency (ω c ) of the first signal and a time derivative of the phase noise of the first signal (dφ n (t)/dt); and 
 integrating the second signal to generate a third signal, the third signal being a measure of the phase noise of the oscillator. 
 
     
     
       20. The non-transitory machine-readable medium of  claim 19 , wherein:
 a) the generating of the second signal from the first signal comprises generating at least one of a current signal or a voltage signal based on the frequency of the first signal, b) the generating of the second signal from the first signal comprises using a frequency-to-current converter circuit and utilizing the first signal to a generate a current signal based on the frequency of the first signal, and c) the integrating of the second signal comprises using an integrator that substantially attenuates near-zero frequency signals.